Coating of articles

Abstract

A method and apparatus for coating a hollow article with at least two coating materials, said method comprising the steps of applying a first coating material to the article and drying or partially curing at least the surface of the first coating before the application of the second material. Thereafter the two coatings may be fully cured together or alternatively the second coating material may be partially cured in readiness to receive a further coating. The preferred curing means is a gas flame.

I claim: 
     
       1. A method of coating a container body with at least two successive coatings, said method comprising the steps of applying a first fluid coating of a heat curable polymeric coating material to a container body; passing the coated container body rapidly before at least one flame source to only partially harden the first coating but sufficiently to permit application of a second fluid coating; applying a second fluid coating of organic coating material to the only partially hardened first coating; and thereafter fully curing the two coatings. 
     
     
       2. A method according to claim 1 wherein the flame impinges simultaneously on the first coating for a period of time within the range 0.5 to 10.0 seconds. 
     
     
       3. A method according to claim 2 wherein the container body is rotated to present the entire container body to a flame on a fixed burner. 
     
     
       4. A method according to claim 1 wherein the first coating includes a conventional slip inducing lubricant used in can manufacturing, at least part of which is removed from the surface of the first coating by the flame, and the second coating also has a conventional slip inducing lubricant used in can manufacturing. 
     
     
       5. A method according to claim 1 wherein the first and second coatings are fully cured after the application of the second coating and before the application of a further coating. 
     
     
       6. A method according to claim 1 wherein the first coating is presented to the gas flame for a period of time sufficiently short to be appropriately measured in seconds as opposed to minutes. 
     
     
       7. A method according to claim 1 wherein the first coating is a base coating and the second coating is a printing ink. 
     
     
       8. A method according to claim 6 wherein the period is less than 10 seconds. 
     
     
       9. The method of claim 1 wherein the container bodies are cured at a rate on the order of 1000 cans per minute. 
     
     
       10. The method of claim 1 wherein the container bodies are cured at a rate on the order of 1000 cans per minute with a heat input on the order of 580,000 BTU per hour.